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A coffee chain states that its paper napkins are made of "coffee silver skin":
The explanation on the right says it is "coffee bean skin"---the husk.
Searching the internet about it, I can just find about silver skin in meat.
Is there more to know about "coffee silver skin"? For example, I wonder if all or part of the husk is part of it, and also why the term is "silver" (this could be a different question---please comment or ask it yourself).
Silver skin is the name generally used when it is still on the green beans. This thin but tough layer is lightly colored (sometimes similarly to the paper product in your question) and mostly translucent. It allows the green color of the bean underneath to be seen. After roasting (when it begins to loosen and fall off) it is more properly called chaff.
Since the paper is likely made of chaff collected from the roasting process (easy to collect since nearly all roasters have a mechanism for separation) is actually an excellent reuse of chaff. "Chaff paper" just doesn't have the same ring since generally chaff is thought to be a byproduct to be discarded.
The silver skin is the innermost layer of the coffee cherry surrounding the pit/seed (green coffee bean). It is a tough substance to remove and different processing techniques remove varying amounts (dry process coffee removes the least and dry process coffee produces the most chaff when roasting). Roasting the coffee both dries the silver skin and causes it to split as the coffee bean expands, so it comes off fairly easily during the roasting process given some agitation.
TL;DR Silver skin is recycled/re-purposed coffee skin also called coffee chaff.
Before coffee beans are roasted they contain about 11% internal moisture, if you look at a green (unroasted) coffee bean next to a roasted one you will notice the green bean is much smaller and has a thin skin, called silverskin or chaff.
The heat of the roasting process converts the internal moisture into steam causing the skin to heat up and the bean to expand. When roasting is completed the chaff falls off and is removed from the roaster. Like coffee, chaff contains a high nitrogen content which makes it a valuable product for environmental purposes, and each roast produces about 3.2 pounds of chaff. As part of our commitment to consciously great coffee we have found a way to recycle the chaff from every roast instead of tossing it into the dumpster. Since 2008 we have partnered with a company called Reconserve that converts bulk food waste materials into animal feed and who’s guiding philosophy is: recycle, reprocess, resource conservation. Reconserve picks the chaff up from our roasting facility in Sacramento, blends it with other bakery byproducts, and produces a feed supplement for dairy cows. We currently produce about 4,000 pounds of chaff each month, this means since 2008 we have recycled about 320,000 pounds of chaff into feed for cattle. We take our commitment to sustainability seriously and make sure that we are constantly evaluating every step of our process to see where we can make improvements. When you purchase ecoGrounds coffees we want you to know you are choosing a high quality coffee that has a positive impact on the environment and global community.
Source: http://www.ecogrounds.com/story/coffee-chaff
Additional information on the patent below: http://www.google.com/patents/US7927460
